Conventional film and more recently, digital cameras, are widely commercially available, ranging both in price and in operation from sophisticated single lens reflex (SLR) cameras used by professional photographers to inexpensive “point-and-shoot” cameras that nearly anyone can use with relative ease. Unlike conventional film cameras, however, digital cameras include image capture electronics that convert light (or photons) into electrical charge. The electrical charge accumulated on each photo-cell (or pixel) is read out and used to generate a digital image of the scene being photographed.
Generally, the resolution of digital cameras is limited by the number of pixels. If the camera does not have enough pixels to represent smooth lines, individual lines may appear jagged (e.g., as “stair-steps”) and/or the image as a whole may appear grainy. In addition, the color of individual pixels in areas of high-contrast and/or fine detail may be erroneously represented as the primary colors registered by the individual pixels and appear as “color artifacts” in the photograph. These undesired effects are known in the digital photography arts as aliasing (and color aliasing).
Aliasing may be reduced by providing more pixels in the camera. For example, the resolution of conventional 35 mm film is estimated to be the equivalent of about 20 million pixels (or mega-pixels). However, most digital cameras in the marketplace today have about 5 mega-pixels. Although cameras having more than 5 mega-pixels are available, these tend to be expensive and bulky.
Cameras are also available with anti-aliasing filters. Anti-aliasing filters shift the light being exposed on the pixels to slightly “blur” the image and thereby reduce aliasing, e.g., by making jagged lines appear smooth or colors blend together. However, the degree of blur cannot be controlled by the use, and therefore may not provide the image sharpness the user desires for certain photographs.